Centralized traffic control system of the normally deenergized reversible coded track circuit type



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. CENTRALIZED TRAFFIC CONTROL SYSTEM OF THE NORMALLY DEENERGIZEDREVERSIBLE CODED TRACK CIRCUIT TYPE Filed May 29, 1945 v8 Sheets-Sheet 2LA 45B W424 m MP 1. w A 5271' "@4251 255 B4 4425K 1-.-- f-15* 4'1 I B"-i&5"-i lb; w m w c 'c B f w w" 21 F E z 1' cQ-U g: 3 5 751V 550 +0 I.9 fiiasv 1 0 yam; 11K

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CENTRALIZED TRAFFIC CONTROL SYSTEM OF THE NQRMALLY DEENERGIZEDREVERSIBLE CODED TRACK CIRCUIT TYPE Filed May 29, 1945 8 Sheets-Sheet 4H5 4L4 41:1: W m

May 12, 1953 H, .s YOUNG 2,638,535

CENTRALIZED TRAFFIC CONTROL SYSTEM OF THE NORMALLY DEENERGIZEDREVERSIBLE CODED TRACK CIRCUIT TYPE Filed May 29, 1945 8 Sheets-Sheet 5INVENTOR. Hezz y 81 21113 7 HIS ATJWBZVIK May 12, 1953 UNG H. S. YOCENTRALIZED TRAFFIC CONTROL SYSTEM OF THE NORMALLY DEENERGIZEDREVERSIBLE CODED TRACK CIRCUIT TYPE .8 Sheets-Sheet 6 Filed May 29, 1945F'" fg -i i 71367 737'! MP 5 757] M 1 71273 ii? I W 1a 7522: i i i q 52623 1 3622 1 i ag-D EU 'HIS Henry 45'. Young ATTORNEY.

H. s. YOUNG 2,638,535 CENTRALIZED TRAFFIC CONTROL SYSTEM OF THE NORMALLYDEENERGIZED REVERSIBLE CODED TRACK CIRCUIT TYPE w 3 9 5 1 9 a II- 2 2 v.1 m

y d a .m M i F 8 Sheets-Sheet 7 I L 811E IN VENTOR. Be ay 5'. Yzzzzg. BY

HIS ATZWIMZ'K May 12, 1953 CENTRALIZED TR H. S. YOUNG AFFIC CONTROLSYSTEM OF THE NORMALLY DEENERGIZED REVERSIBLE CODED TRACK CIRCUIT TYPE 8Sheets-Sheet 8 Filed May 29, 1945 I i l 1 'a l |a B rk'h {B 1025 1am; I'1 1034310! F 1 c zalw 1 B mm- 1 1025" I 4% 102/11 d I N VEN TOR.

Henry Lil many.

H15 ArTyBNz'I i Patented May 12, 1953 CENTRALIZED TRAFFIC CONTROL SYSTEMOF THE NORMALLY DEENERGIZED RE- VERSIBLE OODED TRACK CIRCUIT TYPE HenryS. Young, Wilkinsburg, Pa., assignor to Westinghouse Air Brake Company,a corporation of Pennsylvania Application May 29, 1945, Serial No.596,470

- 11 Claims.

My invention relates to railway traffic controlling apparatus forgoverning the movement of trafiic overstretches of single track, overwhich traflic moves in two directions. More particularly, my inventionrelates to a centralized traffic control system for railroads of thenormally de energized reversible coded track circuit type, such as isshown, for example, in Letters Patent of the United States No.2,344,573, issued March 21, 1944, to James J. Van Horn, which patent wasreissued as Re. 22,915 on September 16, 1947. In the system of thispatent, the trafiic direction through the blocks is set up and the headblock signals are cleared by manual control from a central oflice bymeans of an intermittently operated code type communication system, suchas that shown in Letters Patent of the United States No. 2,229,249,issued January 21, 1941, to Lloyd V. Lewis, and employing cascadeconnected reversible track circuits of the continuous code type for theprotection of trafiic movements. Systems of this type possess theadvantage that no line wires are needed, other than a pair of wiresextending the length of the controlled territory for telephone and codecommunication between the control oiiice and the field stations of thesystem, and such Wires as may be required to supply power to isolatedlocations.

One feature of my invention is the provision of a system of the typedescribed which automatically assumes a normally deenergized conditionwhen its operation is not needed, thereby reducing the power consumed bythe signals and track circuits to such an extent as to render itpracticable to energize them by primary batteries and thereby eliminatethe necessity for a power line along the tracks except for relativelyshort stretches, since in the majority of cases a supply of powersufiicient to operate the trackswitches and other apparatus at the waystations is attainable by connections to local nearby power lines.

The system of my invention is arranged to be set into operation, oneblock at a time, by the transmission of control codes from the ofiice tooperate traflic relays at the exit ends of the blocks for energizing thetrack circuits in the desired direction, which codes are transmittedautomatically when required, as the result oithe manual initiation ofother control codes for transmission to the entrance ends of the blocks,for the purpose of clearing the head block signals by which trafiicmovements into the blocks are governed. The track circuits are arrangedtoprovide the suitable track occupancy and trafiic direction indicators.

The coded track circuits as shown herein are of the low frequencycontinuous code type, em-

ploying battery currents interrupted at the rate of '75 times per minuteto provide caution signal control and to control the block indicatoratthe office when the block embraces only one section, or at the rate of120 or 180 times per minute to provide proceed signal control, the 180code selectively controlling the block indicator in case the blockembraces more than one section.

Briefly described, my invention is embodied in apparatus at the controloffice for governing the traffic relays at the ends of 'a block, inanormally deenergized manualblock signaling system of the general typeshown in the hereinbefore mentioned Van Horn Reissue Patent Re. 22,915..For this purpose, ,I provide two electrically interlocked directionlocking relays at the office (LF'K and RFK) controlled by the signallevers. These relays correspond generally to relays SLP and 8RP of thepatent referred to, but a trafiic lever such as the lever 8 whichcontrols these relays in the patent is not needed, and my directionlocking relays are controlled according to the position of thesignallevers by block indication relays (LBK and RBK) governed by indicationcodes, but with improved circuits requiring only one indication channelinstead of two as in the patent referred to.

. My invention includes means rendering the trafiic relays at the endsof the blocks operable between their normal and reverse positions onlywhen both direction locking relays are released and indicate that thetrackway system is deenergized. Under this condition the operation ofthe usual code starting button associated with a signal lever which hasbeen reversed, by which the same starting button again, with the signallever in its normal position, at any time prior to their completion, asindicated by the recep tion of an indication code which indicates theclearing of the corresponding signal. The block indication relay whichis operated by this code energizes the corresp'onding direction lockingrelay, which relay then serves to maintain the es-- tablished directionof traffic when the entering signal has been cleared or as long as atrain occupies any portion of the block. Another .icature of myinvention resides in the provision of means causing the trackway-systemto revert autornatically to its deenergized condition when no longerneeded. This feature is embodied in'cir cuits controlled by theblockindication relays which serve concurrently to release the operateddirection locking relay and to-Jinitiate-thc automatic transmission of acontrol code to the exit end of the block in response to the r'ecep tionof a block clear indication from the entrance end when the block isvacated by a train,' provided the lever for the enteringJsignal hasalready been restored to its normal .posi* tion by the operator,this'ic'ontrol code serving to restore the operated tranic relay toitsnormal inactive condition.

A further feature of my invention is the pro vision of improved meansrequiring cooperation by the central office operator to eifect therelease of electric switch locks for safeguarding theo-pera-tion ofoutlying. hand throw switches, the arrangement being suchthat for atrain movement from the main track to the side track, the-hand throwswitch may be unlocked byv the-trainbrew provided. the train occupies ashortde'tector section in the main trackadjac'ent the switch. For amovement from the sidetrack to the main track, the central ofiiceoperator moves a three position switch lever for the switch to aleft-hand o'r right=hand position depending upon the direction the trainis to-move after entering the main track, thereby starting thetransmission of a control code to the station at theeXit end of theblock to setup the track circuits for the block in thecorrespondingdirection. The'train crew cooper-ate by removingarpadlockor the like to open a contact in a localcircuitat the switchlocation. If the entire block is vacant, the setting up of the trackwaycircuitsresults in the transmission of a block clearindication from thestation at the entrance endan'c this in'turn initiates the transmissionof a control code trom the dill-cc to: the station at the entranceend'by which steady current is temporarily supplied to the track circuitsystem, blocking the reception df'coded current and causing thetransmission of a block occupied indication to the'office to holdtheexisting direction established.- A'furthereffect of the steadycurrent impulse is to reverse the direction of the coded track circuitsbetween the entrance end of the block and the switch location, "codedcurrent being supp-lied to the track rails at both ends of the blockafter the steady current impulse is terminated. The switch becomesunlocked when codedcurrents are 'received at the switch location, fromboth directions.

When the operator is advised by the train'crew that the train hasentered the main weekend that the hand throw switch is againlocked'normal, he restores the operated switch lever to normal, therebytransmithng code by which thetrackway apparatus is restored to its usualcondition for one direction operation, the apparatus conditionwhen thetrain vacates "the-block.

indicated by the miniature track diagram extending across the top ofthese views, while Figs. 2A to 2F, inclusive, show a plan of thecorresponding stretch of track together with the trackwa'y apparatus andcircuits.

The drawings may be arranged in different ways to illustrate thecircuits for difierent portions of the system. Generally the controlledterritorycomprises a succession of single track blocks of variouslengths connected by passing sidings', in which case the operatorscontrol panel comprises a series ofpa-nels, one'for each station,corresponding toFigs. 1A and 1B, arrangedalternately. These'twoviews,'with Fig. 1B atthe right of Fig. 1A, illustrate theinterconnected of iice circuits for the control of a :typicalxblockcontaining a .passing'siding and extendingbetween two opposing signalsERA and ALA. The corresponding wayside circuits are shown inTF'igs. 2A.and 213, by placing Fig. 213 at the rightof Fig. 2A.

When 1A is placed at theright .ofFig." 13,- these twoviews illustratethe .o fiice CilCllitSlfOl' the control of a single track blockextending. between the opposing signals ABA and 2LA. When the block issoshort that 'nointermediate signals are-needed, the correspondingwayside'circuits are illustrated by placing Fig. 2A directly at therightof Fig. 2B. A longer block having twosets of intermediate signals with 1an outlying hand throw switch l'W is illustrated by placingli igs. 213,20, 2D, 2E and 2Aside by side in order. A block having one set ofintermediate signals witha hand throw'switch 9W nearby is illustrated byplacing Figs. 2l3j2l a-nd2A side by side iii-order. The switch lockcircuits of Fig.'2D are those used when the distance from the switch tothe nearest signal is 'sufficient toprovide the desired minimum approachlighting distance for the signal, while Fig. 2F comprises a modificationof Figs. ZD-andZE which is'used whenthe distance to the nearest signalis less than that required for the'control of the signal lightingcircuits.

Similar reference characters refer to similar parts in each of theviews.

To simplify the circuit drawings, only the terminals of the localsources of current for energi'zi'n'g the relays are shown, these beingdesignated by the reference characters Band C, respectively, these localsources as well as the'tra'ck batteries TB being preferably of theprimary battery type. Each track switch and railway signal is identifiedby a number, the signal designations also including the letter L or R toindicate the corresponding direction of trafiic movements to the left01- right, respectively. Each relay is identified by a letter orcombination of letters, prefixed by the designation of the switch orsignal with which it is associated.

The communication system connecting the control office with the stationsat the ends of the passing sidings may be of any suitable type and asshown is to be understood to be that described in a publication entitledCentralized Traffic Control System-Time Code Scheme, Manual No. 504-13,published by The Union Switch and Signal Company, Swissvale,Pennsylvania. This system corresponds generally to that of LettersPatent of the United States No. 2,229,249, issued January 21, 1941, toLloyd V. Lewis, modified to provide two. additional control steps forthe control of two trafiic directions relays at each station, such asthe relays 2LFS and ZRFS of Fig. 2A.

Consideration of the detailed mode of operation of the communicationsystem is not needed for an understanding of my invention, and it isdeemed suificient to point out that coding units are provided at theoffice and at each field station .which are connected by a pair of linewires indicated diagrammatically by the line Y-Z onthe drawings, overwhich codes are transmitted in either direction one at a time forselective communication between the different oflice panels and thecorresponding stations. Each office panel includes a starting relay suchas the relay IST of Fig. 1A which is energized by the momentaryoperation of a push button such as ISTB to initiate the transmission ofa control code by which a selector relay such as relay OIS at the officeand a delivery relay ID at the corresponding station are selectivelyenergized to temporarily establish a group of seven communicationchannels, represented herein as a group ofwires I to 1, inclusive,between the oifice panel and the selected station. The office panel ofFig. 1A, for example, is associated with a field Station No. 1, shown inFig. 2A, and it is to be understood that when channels I and 3 areextended to Station No. 1 they complete circuits by which the poweroperated track switch IW may be operated to normal or reverse underproper traffic conditions to correspond with the position of contact aof the switch lever ISW, Fig. 1A, in the manner shown and described inPatent No. 2,229,249. Channels 2 and 4 are used to control the twodirection relays 2LFS and ZRFS already referred to, which relays governthe energization of thecoded track circuits for the blocks extending inopposite directions from the station, while channels 5 and I governoperation of the two signal control relays ZRHS andfill-18in accordancewith the position of the signal lever ZSG of Fig. 1A, these relayscorresponding to the similarly designated relays of the patent. Channel6 is idle as shown, but in practice is used for the control of amaintainers call signal or the like.

. The initiation of an indication code by the coding unit at a fieldstation results in the temporary energization of a selector relay suchas the relay IS, Fig. 2A, and of a delivery relay such as the relay OIDof the corresponding ofiice panel, to establish another group of sevenchannel-s 9 to I5, inclusive, over which a selected group of indicationrelays K at the oflice are positioned to correspond with the conditionof various relays at the station. Relays INWK and IRWK, Fig. 1A, forexample, are controlled over channels 9 and II, respectively, fromStation No. 1, to correspond with the positions of the normal andreverse switch indication relays INWP and IRWP,,Fig. 2A, which reflectthe position of the track switch IW, and control the usual switchindication lamps, not shown. Relay ITK is energized over channel I0 bythe release of arepeater relay TP of the track relay ITR, when thedetector section ITior switch IW is occupied, to light the OS lamp ITKEin the track diagram. RelayslL K nd ZRBKare b oski d a i n r lays. RelayZLBK is controlled over channel I2 by a relay 2LI-I or ZLD, Fig. 2A,which is energized when the track sections of the block extending fromStation No. 1 to the next station at the left are set up for trafiicmovements from right to left, and these sections as well as the detectorsection 3T at the leaving end of each block are all unoccupied. Relay2LBK controls a direction locking relay 2LFK-, Fig. 1B, of the adjoiningpanel at the left of Fig. 1A. The corresponding relay 4LFK in Fig. 1A iscontrolled by the block indication relay ILBK, Fig. 1B, located in theadjoining panel at the right of Fig. 1A, and relay 4LBK is controlledover channel I2 by relay ALI-l, Fig. 2B, which is energized when switchI is normal and the track sections IT, 2-4T and ST of the blockextending from Station No. 1 to the next station at the right are set upfor traffic movements from right to left and are unoccupied, or whenswitch I is reversed, if sections 2-4T and 3T are unoccupied.

Relay ZRBK, Fig. 1A, is controlled over channel I4 by relay 2RI-I, Fig.2A, which is energized when the track sections I T, 2-4T and 3T of theblock extending from Station No. 1 to the next station at the right areset up for traflic movements from left to right and are unoccupied, withswitch 3 normal, or if switch 3 is reversed, when sections IT and Z-ATare unoccupied. Relay ZRBK controls the direction locking relay ZRFK,Fig. 1A. The corresponding relay 4RBK, Fig. 1B, which controls thedirection locking relay IRFK, is controlled over channel I4 by a relay4111-11 or 4RD, Fig. 2B, which is energized when the track sections ofthe block extending from Station No. 1 to the next station at the leftare set up for traflic movements from left to right and these sectionsas well as section IT are unoccupied.

The relays 2RBK, ZRFK, ILBK and 4LFK jointlycontrol a directionalindicator lamp ZRE or ILE which is lighted when the trackway system forthe corresponding block is set up, and also a block indicator lamp 2-4BEwhich is lighted when the established block is occupied by a train.

Relays ZLHK and ZRI-IK are controlled from Station No. 1 over channelsI3 and I5, respectively, to indicate the conditions of the signals atStation No. 1, and control the usual indication lamps associated withthe signal levers as in Patent No. 2,229,249 hereinbe'fore referred to.As shown herein, relay ZRHK is energized when signal ZRA or 2R3 iscleared, and relay ZLHK when signal 2LA or ZLB is cleared. In addition,both relays 2RHK and ZLI-IK are energized by the operation of a relayIASP to provide a distinctive indication when certain time lockingapparatus associated with these signals is in operation.

It will be understood that an indication code is initiated whenever anyof the relays which control channels 9-45 changes its position, or ifthe change occurs when the communication system is in use, "as soonthereafter as it becomes available, and also that the same channels I-Iand 9-I5 are used at different times for communication between thecities and each of the stations. I

The block signals as shown herein are of the well-known searchlighttype, each having a three position mechanism identified by the referencecharacter G prefixed by the designation of the corresponding signal asshown in the track plan, by whichthe signal is caused to indicatecaution or proceed when energized in a'normal or reversedirection,respectively, and to indicate stop when deenergized. Themechanism for each signal governing high-speed movements, such asmechanisin: QRAG; Fig. 2A.,- forv signal-ERA, controls a repeating relaysuch as rela :ERPC forgoverning the polarity of the-current supplied tothe mechanismzfor the distant signal in the rear, and when the twosignals at the same location such as signals ERA and 2R5 are both atstop; an indicatron relay such as relay ZRJGP is'energized, which relaycontrols the corresponding signal indication relay QRHK at the ofiiceand ':also controls an approach locking relay such .as relay'ZRAS)V1llCh provides the usualtime and: approach locking for theassociated track switch and for-the opposingsignals at the opposite endof the block. Each signal having a .traclrcircuit inrapproach theretois-:norm'ally dark, and theisignal lamp, shown below the correspondingmechanismon the drawings, is lighted by-the'operation of an ap preachrelay when a train approacheswvithin range or the signal. The approachrelay may be connected either in multiple with the track circuit acrossthe track cattery TB, as illustrated by'relay EZRAR, Fig. 2A, orrnay beconnected in series with the track circuit like relay. BRAR, Fi'gQQC.

The-trackway system, which I shall now describe in detail, includescontinuous track circuits for all main track. The switch sections eachhave a track relayTR which is steadily energizedby a track battery TB.Theremaining track circuits in the main track are or" the reversiblecoded type, connected in cascade when the block includes two or moresections. Each coded track circuit has-a code following track relay ofthe biased polar ty e, such as the relay ZLTR, Fig. 2A, at each end,connectedacross the track rails over the back contact I) of a "codetransmitting relay such as the rel'ayfiRCT, which relay when energizedconnects a track battery TB'across the track rails, but withoutoperating relay ZLTR because of the relative polarity of the connectionsand because relay ZLTR is shunted b front contact a of relay ZRCT. Eachcode following track relay controls a slow acting repeater relay such asrelay ZLTF which relay remains picked up when relay ZLTR is respondingto coded current to complete circuits for the usual decoding transformerDT.

When a trafiic relay such as relayZRFS, Fig. 2A, is energized by thecentral ofiice operator, the closing of its front contact I)completes-an obvious circuit for energizing 'a code "transmitter lt CTor l-86C'T over contacts of the repeating relay ZRPC for the adjacentsignal. The code transmitters are of the pendulum type and each opcratescontinuously when energized. When the detector track section IT isunoccupied, the closing of contact a of the trackrep'eating relay ITPprepares a circuit for rela ZRCT which is comple'ted periodically overcontact a of relay 150T or lfiilCT and relay 'QRCT is thereby caused tosupply'current interrupted at the '75 code rate to the track rails ofthe section at the left of signal ERA when relay ERPC is released, andat the 180 code rate when relay ZRPC is energized.

In Fig. 2A, the relays 2W8, RTE and 2TES operate only in connection withelectric switch lock control as hereinafter described, and for throughtraffic control, relay ERFS energizes a repeating relay ZRFSP over acircuit from terminal B at contact of relay ERFS, back contact a ofrelay ZW S; back 'contacts b of relays ZTES and 'ZLTF 8 throughrelay'.ZRFSP to terminal C, 1 and when relay 2RFSP isvenergized,sthe.circuit'for-relay ZRCT is completed fromterminaliB atcontact a of thecode transmitter 180071 or. 1=5CT over-the frontzorback contact 0 ofrelay ZRPC, frontcontact-b of relay ZI tESP; contact 'b'of theapproachlocking relay ZLAS .for theopposing signals; contact ai of the;repeating relay ITP for the track relay ITR through relay 2RCT toterminal C.

Assuming for the present that the single-track blockinithe rear ofsignal ZRA includes onlyione codedtrack section, as illustrated byplacing Fig. 213; at the left of Fig. 2A, itwillbe seen that whenthisusectionis .unoccupied,..the code operationof relay ZRCT is repeated.byztheltrack .re1ay-4RTR, thereby energizingrela-y il'titl and throughthe usualxdecoding transformer DTalso energizing the-code detector'relayitRl-I. .In addition, a decoding relay 4RD is selectivelyenergized through a resonant decoding lunit 'I'BIlDU when relay '4RTR isoperated atthe codev rate.

If now the operator causesthe .signalcontrol relay lRI-IS tobecomeienergized, and if .the1detec, torsection ET is vacant, so thatrelays: tTRand 3TP, are energized, :and ifxrelay RH is 'alsox'energized,a circuit is completed :for'energizinga block repeating relay I4RBP, andtherebyreleasing theapproach locking. relay 4RAS to lock switch 3W,ancldepending upon the position vofsswitch 3W, .to complete a circuitfor energizing. mechanism SRAG or IZRBG toclearsignal v lRA or ARB, andto release the signal indication relayx iRGP.

The-circuitfor relay lRBPmay be traced from terminal B at back-contact dof relay QLFS, shown-near the right-hand margin iniFig. 213, over frontcontact a of relay lRl-I, back contact 0 ofz'relay JlLHS, frontcontac'tb of relay .3TP, contacts a ofrelays 3RWP'and 3NWP, front contact c or eof relay 4RHS-throughrelay fiRBP .to terminal C; Relay iRAS is normallyenergized over the circuit from terminal B at-oack contact 12 of relayiRBP, contacts a of relays 4RPO-and 4RGPand its own front contact a and.winding to terminal C,-which circuit is opened by relay lR-BP, and ismaintained open after the signal clears, by the release of relay GRGP.

.The circuit for mechanism 4RAG extends from terminalB;atlfrontcontactgbof relay IRBP over front-contact c of relay 4LAS, backcontacts c of a'tim-e elementrelay STE and of relay ARAS, and .thence over contacts aof. relays ARD-Aand 4RD; back contacts I) of relay BRWP, mechanism 4RAG,front contact b of relay '3NWP, contacts b'wof relays ARD-an'd JllitD'A,contact a cfrelay 4RBP andcontact d of relay ARI-IS to terminal C atcontact In of the track relay STR. 7

' The, circuit for mechanism IRBG differs from that-tormechanism.4RAGonly in that it is :completed over the front contact 12 of relay 3RWPand the back-contactvb of relay -3NWP., asis clear from the drawing.

Considering next :the block comprising :the main track of the doubletrackstretch, it will be assumed that. thetrafilc relay -4FRS has beenenergized along with relay 'AlRHfEl, so as'to set relay idRCT intoperiodic operation to supply coded current to the track rails of thesection in the rear of signal ARA. Placing FigJZAzat the-left of'FigJZB, and assuming that the main track block includes only one codedtrack section, if this section is unoccupied the code operation of relaydRCT will be repeated by the track relay 2RTR, energizing relays ZRTFand' ZRI-IR; and when relay zara is operatedat the 180 code rate,also-energizing r-elay If now the oper ator causes the signal controlrelay ZRHS to become energized, if switch [W is normal and section ITvacant, the block repeating relay ZRBP becomes energized, therebyreleasing the approach locking relay ZRAS to complete a circuit forenergizing mechanism ZRAG to clear signal 2RA, and to release the signalindication relay ZRGP, the circuits being generally similar to thoseassociated with signal 4RA as already traced.

For a movement into the passing track of the double track stretch, relay2RHS is energized with switch lW reversed, in which case the circuit forthe block repeating relay ZRBP includes front contact a of relay IRWPand extends to terminal B at back contact 6 of relay ELI-IS, andmechanism ZRBG is energized to condition signal ZRB to indicate cautionover circuits which are independent of relays ZRH and 2RD, as shown bythe drawing.

- Assuming now that the system is set up for a movement from left toright, as above described, it will be seen that when a train passessignal ZRA at clear, entering section IT, relays [TR and ITP release.The opening of contact I) of relay ITR releases mechanism 2RAG, causingrelay ZRGP to be reenergized. Relays ZRBP and 2RHSare released by theopening of contacts I) and f of relay ITP, and the closing of backcontact 17 of relay ZRBP completes a circuit including contacts a ofrelays ZRPC and ZRGP and contact of relay ITR to pick up relay ZRAS.Relay ZRI-IS opens its front contacts 0 and d in the circuits for relayZRBP and mechanism ZRAG, and relay ZRAS opens its back contact 0 in thecircuit for I mechanism 2RAG, so that signal 2RA remains at stop aftersection VI is vacated. In Fig. 215, at the right, relay lRFS standsenergizedunder the condition assumed so' that its back contact b isopen, rendering the energization of the slow release relay 4RAP-dependent upon the periodic operation of the code following approachrelay ARAR. Relay 4RAR is connected across the track rails and issupplied with coded current by relay lRCT, and is so adjusted that theshunting effect of an approaching train causes it to fail to respond tothe code when the train comes within range of signal 4RA, whereuponrelay ARAP releases and closes its back contact a to light the lamp forsignal dRA. The lamp for signal 4RB is continuously lighted, in view ofthe fact that no track circuits are provided for the upper passingtrack.

' When the train passes signal ARA, entering section 3T, relays 3TB and3'I P release and the lamp for signal ARA is maintained lighted and thelamps for signals ALA and 4LB become lighted due to the closing of backcontacts 0 and e of relay 'IP.

Mechanism ERAG releases when the train enters section 31, likewiserelays 4RBP and 4RHS, and relays lRGP and R-AS become reenergized, overcircuits similar to those of Fig. 23 already described. A directionalstick relay dRES also becomes energized at this time over the circuitfrom terminal B at back contact g of relay 3IP, front contacts 0 ofrelays SNWP and ARI-I through relay ARES to terminal C. Relay 4RES isheld energized over a stick circuit including its own contact a and backcontact 0 of relay 4RI-I, and by closing its contact I: maintains thelamp for signal 4RA lighted as long as the train occupies the blocksection at the right of section 3T.

In the foregoing I have'assumed that the single track block betweensignals 4RA and 2LA is relatively short and includes only one tracksection. I shall now consider a longer block comprising three blocksections, such'as illustrated by interposing Figs.- 2C and 2E betweenFigs'ZB and 2A. In this arrangement, the coded currentsupplied to thetrack rails by relay ERCT at the leaving end of the block'is received bythe code following track relay SRTR, Fig. 2E, energizing the slowrelease relay BRTF and completing a circuit periodically from terminal Bat back contact a of relay SRTR over contacts aof relays ilRTF and iiLTFto energize a code following repeating relay B'IP. Contacts b and c ofrelay BRTF complete connections over the contacts of relay STP fromterminal B to the decoding transformer D1 and from the latter to thedecoding relay BRH, whereby relay 8RH becomes energized in response tothe code operation of relay SR'IR when the block section at the right ofsignal 8R is unoccupied. When signal 2RA indicates caption or proceed,relay 2RPC is energized and the frequenoy of the code supplied to thetrack rails of this section is shifted from '75 to impulses per minute,in which case relay 8D is selectively energized along with relay SRI-I.Relays BRI-I and 8D control mechanism 8RG to condition signal 8R toindicate caution in response to the 75 code and to indicate proceed inresponse to the 180 code, as will be apparent from the drawing.

When relay BRH, is energized, the closing of its front contact 03energizes the associated code transmitter iBiiCT, contact a of whichthen operates periodically to energize relay BRCT to supply currentcoded at the 180 code rate to the track circuit for the sectionextending to' signal GR in the rear of signal 8R, to operate the codefollowing track relay SRTR when this section is unoccupied.

' The circuit for relay 8RCT extends from terminal B at contact a of thecode transmitter [890T over back contact e of relay 8LI-I, front contacte of relay tRl-I, front contact d of relay SRFT, back contacts 0 ofrelays SRS and 8LS, back contact 11 of relay SLTF through relay 8RCT toterminal 0.

In Fig. 2C, relay iiR'IF is energized by relay liRTR, and relay G'IPresponds to the 180- code operation of relay BRTR to energize relaysGRI-I and 6D, thereby energizing mechanism GRG to condition signal 6R toindicate proceed. With relay 5D energized, relay EiRH energizes theassociated code transmitter IMCI' and causes relay iiRTC to supply 180code to the section in the rear of signal 8R, over which the track relayARTR of Fig. 2B is controlled. If this section is vacant, relay 4RTR isoperated at the same rate to energize relays BR'IF, lRH and 4RD, wherebyif section ST is vacant, signal RA or 4R3 may be cleared by the operatorby energizing the signal control relay lRHS as already described.

If a train now passes signal ARA at clear, the

signal is returned to stop by the release of relays 3TB and 3'IPand'relay 3TP releases relay ARI-IS, so that the signal remains at stopafter the block is vacated.

In Fig- 20, at the right. the approach relay ERAR, in series with thetrack battery TB is shunted by a resistor which is so adjusted thatrelay BRAR begins to respond to the code operation of relay BRCT onlywhen the train occupying the section approaches within range of signal6R.

When relay ERAR begins to operate, relay BRAP' is energized to light thelamp for signal 6R, and

if'relay ERH is energized, to cause the directional stick relay 'SRS to'become energized, relay GRS 1 1 energizing the associated codetransmitter 'IECT.

When thetrain enters the-section at the right of signal 5R, relay iERl-Ireleases to restore signal BRto stop. and to hold relay GRS energized,and when the train vacates the section in the rear of signal 81%, relayGRCT supplies coded current thereto to operate relay iR'IRat the'75 coderate, thereby energizing relay ARI-I to release relay tRES andextinguish the lamp for signal 4RA. Relay ERCT is in this instanceenergized over front contact c of relay GRSand the periodicallyoperating contact a of the code transmitter CT of Fig. 2C.

Asthe train proceeds, similar operations occur when the train passessignal 8R. As the train approaches within range of signal 8B theincrease in the coded current in the track rails causes relay SEAR torespond, energizing relay BRA]? to lightthelanip for signal BR and toenergize relay 8R8.- When the train vacates the section in the rear ofsection 8R, relay BRCT supplies current to the section in the rear tooperate relay tR'lZR at the '75 code rate, thereby energizing relayBRI-I and releasing relay ill-ES. Since relay 6D is not energized, thecode transmitter HUCT of Fig. 2C is operated to cause relay iiRCT tosupply current to thesection in the rear of signaltR to operate relayll-1TB at the 129- code rate, thereby energizing relays and ARDA. Relay#RDA serves lilz-erelay. 4RD to reverse the polarity of the current.supplied to mechanism iRAG or 4RBG but without energizing the blockindication relay tRBK: over channel is, whereby signal 4RA or 4R3 may becaused toindicate proceed when signal :tftzin advance stands at caution,and signal RW- p, with a train in the block section in advance of signal8R.

When the train vacates the last track section 11 of the block, relayZRCT? is operated at the 75 code rate to condition signal 3R to indicatecaution-and relays @RCT and SRCT. are operated at the 1% code rate toenergize relay "5D to condition signal SE, to indicate proceed, andrelay. 4RD becomes energized to maintain the proceed indication ofsignal WA or 4R3 and to initiate the transmission of a block clearindication to the office to energize relay lRBK.

In the-foregoing Ihave described the operations or the trackway portionof the system with respect to a-train movementfrom left to right fromsignal ZRAthrough the block extendingto signal ARA-and including themain track of thedouble track; portion, and then through the next blockextending. from signal 4RA throughv the single track-stretch to the nextsignal at the right similar. to signal ZRA.

I shall now. describe the operations of theofl'ice apparatus of Figs.Yin and 1B for controlling such a train movement, starting with theapparatus in its normal-condition as shown, with Fig-.113 at the rig-htofFig. 1A.

To clear signalsZRA and ARA, the operator places the signal levers 28Gand. ISG in their rightehand positions, with the switch levers ISW andSSW normal, as shown, and presses the starting buttons STE and 3STB. Theclosing of contact. a of each button energizes the associated startingrelay IST or 3ST to initiate the transmission of a control code in theusual manner.

The operation of each button also closes a second circuit over itscontact I) to energize thestarting relay for the adjoining panel in thedirection of traflic movement, that is to say, relay 3ST is energized bythe operation of button ISTB, provided that is operated first, and theoperation of 12 buttontSTB energizes a relay similar to relay 5ST in thenextpanci at the rig-ht of Fig. 1B.

The circuit by which button IS'I-B controls relay 3ST extends fromterminal .8 at contact-b of button ISTB over'the right-hand contact d oflever ZSG, contact t of lever iSW, back contacts of relays iLFK andZRFK, wire 23, through relay EST to terminal C. The circuit by whichbuttonSSTBcontrols relay 1ST of the adjoining panel at the right extendsfrom contact b of button 38TH over the right-hand contact d or" lever48%, back contacts I of relays 2LFK and IRFK, wire v2i through the nextrelay iST, at the-right of Fig. IE, to terminal C.

Each signal leverin its right-hand-position closes a circuit forenergizing channel l in the adjoining panel at the right. Thus a circuitis closed from terminal B at the right-hand contact?) of lever 28G,normal contact b of lever ISW, contact e of lever lSG, back contacts dof relays ALFK, lLBK and ERBK, wire 24,-. contact. 0 of the selectorrelay 03S to wire 4, and acircuit is closed from terminal B at theright-hand contact I) of relays :ZSG, contact e of IEVEIQSG, backcontacts at of relays ZLFK, ZLBK and QRBK, wire 25 and thence to wire 4over contact 0 of the selector relay 01s for the next panel at the rightof Fig. 1B.

Thus inresponse to the operation of the two starting buttons threecontrol codes are trans.- mitted, one to Station No. 1 in which channelI is energized over contactd. of relay 01S and contact a of lever ZSG topick up relay ZRl-IS, one to Station No. 2 in which channels 4 and l areenergized to pick up relays lRFS, and tRHS, and one to the nextstationat the right in which channel 4- is energized to pick up a relaysimilarto relay ZRFS. In other words, a signal control relayis pickedup. at the entrance end: of each block, and a traffic direction. relayis picked up at-the next end or" each block, which relays function toset up the trackway apparatus as hereinbefore described.

Similar arrangements are provided for controlling traffic movements fromright to left, the starting circuits being. thoseincluding wires 28 and22..v Channel 2 is used to control the traiiic direction relays QLFS andlLFS, the. circuits for energizing .these relays being those whichextend to terminal B at the left-hand contacts of the signal leversdSGand ZSG, respectively.

When the traokway apparatus for a block is set up and. the enteringsignal cleared, an indicationcode is transmitted, whichin the case.

ofsignal ZRA, for example, results in the. en.- eztgization of theindication,v stick. relays ZRHK. and 2RCBK, whereupon a direction.lockingstick relay ZRFK becomes energized over a branch of thecircuitincludingwires 24 and 4 traced above, extending from. terminal Bat. the right-..

hand contact .b of lever 23G over front contact .dof -re1ay2RBK., RelayERFK is then held energized over .a stick circuit extending to terminal.18 over its own front contact a and front contacts b of relays ZRHKand. Wire 2 3'! is maintained connected to terminal B by the. closing ofcontact e of relay ZRBK, and when either relay ZRBK or ZRFK isenergized, its frontcontact b completes a circuit by which the lamp. ofa direction indicator ZRE is lighted in the track diagram to indicate.the direction of trafiic established.

The set-up for the, block governedv by signal EZRA may becancelledrnanually While the block isclear,'-if desired, by returninglever "28G to normal and transmitting a code to Station No. l to putsignal ZRAto stop. This results in the transmission of an indicationcode from Station No. 1 which maintains relay 2RBK energized andreleases relay 2RHK, and thereby deenergizes relay .2RFK, but before:relay Z-RFK releases, a starting circuit is closed momentarily atcontact .0 of relay ZRHK over wire 23* to pick up relay 3ST andautomatically initiate the transmission of a control code to Sta: tion.No.. 2 in which channel =1 is deenergized, due to the release of relayZRFK. This code releases the trafiic relay lRFS and restores thetrackway apparatus for the block to its inactive condition, theresulting indication code releasing relay 2RBK. The starting circuitreferred to extends from terminal B at the center contact b of lever ZSGover backcontacts cv of relays, ZRHK and ITK, front contacts 1 of relaysZRBK and 2RFK over wire .23 through relay 3ST to terminal C.

Assuming that theset-up is not cancelled, and that a train governed bysignal ZRA enters the block. The release of relay 3TB, restores signalZRA to stop and initiates the transmission of an indication code whichcauses relay ZRHK to release and relay ZTK to become energized; theclosing of contacts b and d of relay ITK holds relay ZRFK energized andcauses lamp lTKE to be lighted. A second indication code is initiated bythe release of relay ZRI-I when the train enters the coded tracksection, which releases relay ZRBK to light the block indicator lamp2-4BE in the track diagram over back contact b of relay 2RBK and frontcontact of relay 2RFK, and a connection to terminal B at back contact 0of relay ZRBK holds relay ZRFK energized after section IT is vacated andrelay ITK released. When the train vacates the last track section 3T ofthe block, relay 23H becomes reenergized, causing an indication code tobe transmitted to reenergize relay 2RBK, extinguishing lamp 2-4BE. Iflever ZSG is still reversed, relay 2RFK is held energized over frontcontact d of relay 2RBK so that the trafiic direction remainsestablished, butif lever ZSG has been restored to normal while the blockis occupied, relay ZRFK is deenergized by the opening of back contact oof relay 2RBK, and the starting circuit from terminal B over the centercontact I) of lever 286 to wire 23 as traced above is completedmomentarily by the closing of contact of relay ZRBK to energize relay3ST and thereby effect the restoration of the apparatus for the block toits inactive condition in the manner already described.

It will be apparent that the operator may hold the trackway apparatus inits active condition after theblock is vacated by leaving lever 25Greversed, as would be the case if he had reenergized relay. 2RHS tocause signal ZRA to clear automatically for a following train. as soonas relay ZRH became energized.

The operations resulting from a train movementthrough the block governedby signal tlRA are similar to those just described, except that in thisinstance the block indication relay lRBK is governed by relay 4RDinstead of by relay 4RI-l because the blocl; includes more than onecoded track section. v H

The operations relating to the opposite direction, from right to left,under the control of the head block signals 2LA and 4LA, or theintermediate signals. 6L and BL, are similar to those '14 described anda detailed description is deemed unnecessary, further than to point outcertain features relating to the meeting of trains at the passingtracks.

Assume, for example, that the operator wishes to reverse switch 3 and toclear signal ALB for a train movement into the upper track. This isaccomplished by reversing lever 3SW, moving lever 48G to its left-handposition and then pressing button BSTB to energize relay 3ST and therebyinitiate the transmission of a control code to Station No. 2 in whichchannels 3 and 5 are energized. The circuit for relay IST including wire20 and extending to terminal B at contact I) of button 3S TB is open atcontact b of lever '3SW, consequently these operations result in thetransmission of only one control code. The switch indication relay 3RWKbecomes energized and relay 3NWK releases in response to the reversal ofswitch SW, and the operator may then clear signal 2RA at the nextstation at the left, for a movement over the lower track up to signal4RA, by placing lever ZSG in its righthand position and pressing buttonISTB, as hereinbefore described, but in the present case the'cirouitsfor relay 2RFK and for energizing channel 4 over wire 24 are completedover contact c of relay BRWK instead of over contact 6 of lever 48G, thelatter contact being open. The circuit for energizing wire 2 overcontact a of relay OIS which extends to terminal B at contact f of lever48G is open at contact 0 of lever 38W, so that relay ZLFS, .at StationNo. 1, cannot become energized, and consequently the operation of buttonISTB results in the transmission of a control code to Station No. 1 bywhich only relay ZRHS is energized, and of a second code to the nextStation No. 2 at the right by which relay ARFS is energized.

I shall now describe the features of my invention relating to thelocking of outlying hand throw switches, as illustrated in Fig. 2D, andshall assume that this view is interposed between Figs. 20 and 2E in thecircuits for the single track block.

Fig. 2D includes out section apparatus by which a short detector tracksection 1T adjacent the hand throw switch 1W and having a steadilyenergized track relay lTR is interposed in the track circuit system.Assuming, for example, that the code following track relay 'IRTR isoperated by coded current received over the rails of the track sectionat the right, a front contact repeating relay 'lRTF is energized andalso a back contact repeating relay 'IRTB to complete circuits wherebyrelay lRCT is caused to repeat the code into the track section extendingto the left, provided the corresponding relays lLTF and 'ILTB for theopposite direction are deenergized.

The circuits for relays 'IRTF, 'IRTB and IRCT extend from terminal Bover back contacts a of relays 'ILTF and l'LTR and front contact a ofrelay 'IRTR through relay 'lR-TF to terminal C, over back contact a ofrelay TRTR and front contact a of relay IRTF through relay 'IR'IB toterminal C, and over front contact a of relay IRTB, back contacts I) ofrelays 'lLTB and TLTF, front contacts a of relays 'ITR and 'INWP', frontcontact I) of relay 'IRTF through relay IRCT to terminal C. Relay 'INWPis an indication relay for switch 1W which is energized when the switchand its electric lock are locked normal.

The electric lock may be of the type shown in Letters Patent of theUnited States No. 1,126,834, granted February 2, 1915, to Walter 15 P.:Neubert. and William. E. :Eim-ith, "andnserves to lock the operating:lever' tforthe switch in itsnormal. positionibys-a latch. attached toSega ment 25 which is held in looking positionhy'the bailtfi of apad-lock. To unlock theswitch for. a movement into the side track, the:train-rnust occupy sectionJIT so as to-release; the track relay lTRrandthe padlochmustbe removed. by the, train crew andthe; segment 25.movedtothe position in which it is stopped hythe locking 10221 In thiposition, a circuit is closedifrom terminahB over baclccontact b ofrelay 1TB, contacts i-l-tfithrcugh magnet lWLyto terminal C, energizingthe magnet tolift vtherlooking dog yil and. to open contact 18 toreleasethe indicating relay TNWP, and permittingsegment 251 .0 be movedto-itsfull. reverse position in which-lever 8 is free'to be operated toreverse the switch.

For movements out of the side track, coooperae tion:;with;thecentraloificeloperator is required; andfthetrafiic control systemmustbeset upifor thegblock which the-train is to enter, in aspeeial mann nasalr adypointed outhereinso .as to enablecoded current to be received atthe switch location from both directions. Assuming that theidirectionin. which the train is to move, after: it enters the-blockis fromlei'tto right, the res cept-ionioi coded current at the switch. locationfrom theright indicates-.thattheportion of the block at the :right'ofthe switch. is either une occupie d,.,or that: the direction of movementof a train inthat portion is away from theswitch. In the latter, case,the current received from the right-is provided lbyenergizing. adirectionalstickrelay, ,such as relay 8RS,L.Eig. 2E; Thecurrent receivedfrom the left; at the switch location. is provided by energizinga stickrelayltws, Fig; 2B. Relay 4WS is energized by operating -the entranceend tramc relay ALFS; to its .exit. end position, "while coded current.is being received .at thcxleftmand end of the block, .andibecomes-enacrazed-following. anoperation of relays 4-TE' and- 4T-E5by-which steady:current is supplied-tothe rails for a time sufficient toterminatethertrans== mission-or coded current from rightto left -over herailsof thesections. at. the leftof the switch.- ll'onthev control ofthis trainimovernent .a three position lever. 75W, Fig. 1B, isprcvidedofsthe push-turn type having two. auxiliary pushJ- cntactsc andb whichclose momentarily-iwhen' the lever rotated. .But one switch loch leveris required :for each. block. containing. a hand throw switch eventhough the block contains; a-- number of: switches at differentlocations-An the block;v

Tow unlocki-a, switch for a movement but of. the side track, whenthe-system is in its normally, deenergized :condition; as shown, i theoperator moveslever 'lSWto the left or right, preferalolyin thedirection the train is to move,

responsezto a request from the train crew, and theyremovethepadlockbaiI-SO soas to-open contact 49 and. to closecontacts-41-49;:- relay 1...,NEW beingthen held energized over-a stick cir cilitaasshown;-

The operation ofiever JSWto the right,=with the-signal levers 28G andiSG-norma-l; energizesrelay .IRZ and. also initiates the transmission ofa control code 'to StationNo. 1 .at the right=ha-ndend-pf the. blockatopick up relay ZRF'S; and" thereby setup: the track circuit system so asto energize relays ARTE, ARI-I, and'AR-D-atthe"lefthand end, providedtheb'lock is unoccupied.-- a

Relay JRZ is: energizedv over: the. circuit :from- 1'6 terminal B at thecenter contacth; of lever. #56; rightehand contactic; of lever: (SW-gcontact a of lever: 28G; back contact (1 of relay AREK: through relay7R2 to terminal 1C.

Relay 1ST is energized over :the: circuit from terminaliB atlcontaots aandp of' leverflSW, back contact i of relayARFK, wire; 21 through rcelay. 1ST to terminal .C, to initiate; the code,:;and channel l isenergized :to pickup relayl'RFSiover the circuit. from: terminal 3 over,the, right-hand contact 11 of lever: "ISW and contactae of lever 25G,back contacts d of relays 1 2LFK, 'ZLBK and ARBK, and thence, as alreadytraced, 7 over: wire 2 5, contact a ofrelay 0lS towire -4.

' When the energization :of .the' track. circuit system by relay. 2RES:is completed, relay 4RD picks up, initiating anindication code whichpicks up i relay ARBK, thereby. lighting the directtionin'dicator lampIRE, and'relay iRFK- picks up overfront contact: 01 ofrelay'illRBKzwhich'is now connected to terminal B at the right hand'contact d of lever ISW.

The opening of back-contact d-of reIay-ARFK deenergizes relay lRZ butbefore relay 1RZ-'releases, relay 3ST- is picked up over front contact dof relayARFK and front contact-moirelay TRZ to initiatethetransmission'of a control code .to Station No; 2,- at theleftehandend 'of-the block.

This-circuit for relay 1ST extends from termi-- nal B at the centercontactbof-leverASG over the'right-hand contact 0: of lever ISW, cer1tercontact 9- of lever ZSGJrQnt contact d of' relay dRFK, frontcontactaofrelay' 7R2, throughrelay'Z'IST- to terminal C.When-relayJRZreleases, this connection from terminal B isextended overthe back contact-a ofrelaylR-Z andfront contact a of relay O3S=to wire2; topick-up relay QLFS, at Station No. 2.

Since under the assumedconditions relay lRTR, Fig. 2B, is nowbeingoperat'edby'coded' track circuit current, relay" 4R1? occupies itsenergized position and when relay 4LES- picks up, the thermal relay lTEisenergizedin'place of relay 4LFSP; over the circuit from-terminal B atcontact 0 ofrelay ALF-S;- back contacta of relay AWS; backcontactb ofrelay 4TES frontcontact I) of relay" QRTF through-relaydTE-to terminalC.RelaylTE-opens-its contact-b; and after an interval of severalseconds-closes its contacta to energize relay ETES- over back contact aof'relay ALFSP, and back: contact I) of-re1ay lWS. Relay 4TES- Diksup,-comp letingza stick circuit at its contact a. and deenergizing relay4TE; and closing a circuit-from-terminalBat contactwdof relay-4TE'S-over back contact c-of relay 4W8, contacts I) of relays lLFSPand'lRAfiS, contact a of relay 3-1 P"throughre1ay 4LCTto terminal C.

Relay ALCT thsrefore loeco nessteadily ener'-- gized, deenergizi-ngrelays 4RTR '4RIT, ARI-1* and 4RD; and supplying; steady current tothetrack rails extending tothe right. R'elaydftfl upon releasinginitiates-an indication code'which" releases relay ARBK to light theblockindicator lamp 4-2BE,'1 relay dlRFK being 3 "held energizedoverbaek-contact c'ofrelay ARBK.

PlaeingFig; ZC'at -the rightof Fig? 2B, it"will be seen that the-steadycurrent received over the track rails from'the leftwill-energize relayGLTR, during the first oiT period-ofthe' code-sup plied to this sectionby relayfiRCIl Relay BLTF thereupon picks up and :opens the circuit"forrelay-GRCT to prevent its further operation-s Be lay-iwspicks: upoverwthe -circuitfrom terminal B at contact 6 of relay GLTF, contact fof relay GRI-I through relay GWS to terminal and its contact b opens thestick circuit for the directional stickrelay GRS. It follows that ifrelay BRS is energized, it will be released by relay 6WS and will notinterfere with the subsequent code operationof relay SLCT. Relay GWS isheld energized-over the stick circuit including its own contact a andcontact e of relay BLTF, and relay 6LCT becomes steadily energized overthe circuit from terminal B at back contact of relay BLH, contact 0 ofrelay 6W8 through relay GLCT to terminal 0, thereby deenergizing relaysBRTR, GRTF, BRH and 6D and supplying steady current to the rails of thetrack section extending to Fig. 2D at the right At the switch location,Fig. 2D, the steady current received over the track rails of the sectionat the left energizes relay lLTR during the first off period of the codesupplied to this section by relay IRCT, and the opening of back contacta of relay 'ILTR opens the circuits for relay 'IRCT, lRTF and IRTB sothat relay 'IL'IR remains steadily energized, relay IRCT remainsreleased, and relays 'IRTF and IRIB release.

-When relay 'IRTF releases, relay 'ILTF becomes energized, and byopening its back contact 0, releases relay INWP, since as assumed,contact 49 is now open.

In the event that the operations being described-are intended for therelease of the electric lock for another track switch in the same blockbut at the right of switch 1W, the bail 50 of the padlock for switch 1Wwould not have been removed and contact 49 would be closed and relay'INWP would remain energized, in which case the energization of relay'IL'I'F would complete a-circuit from terminal B at back contact a ofrelay 'IL'IB over contacts I) of relays 'IRTB, IRTF and *INWP, contact aof relay ITR, front contact b of relay ILTF through relay 1LCT toterminal C, so that relay 1LCT would become energized to apply" steadycurrent to the track rails extending to the right.

-- At the-location where contact 49 has been opened by the train crew,this being the one shown in Fig. 2D as assumed, relay INWP releases,and'the steady current impulse is not transmitted further because thecircuit for relay 1LCT is opened at contact b of relay INWP.

track rails as above described for a time corresponding to the coolingperiod of relay 4TE', Fig. 23, contact b of relay 4TE closes to pick uprelay 4W3, and the closing of front contact 0 'of relay 4WS connectsrelay 4LCT to the contact of the associated code transmitter 15CT orI80CT to cause coded current to be supplied to the track rails at'theleft-hand end of the block. -In Fig.- 2C, relay GLTR responds to thecoded current received from the left and sets relay 'ISTP intooperation, energizing relay GLH to clear signal 6L, and to connect relayBLCT to the contacts of the adjacent code transmitter I80CT to supplycoded current to the track rails extending to Fig. 2D at'the right,where relay 'IL'I'R res'ponds to this coded current and energizes relay'ILTB along with relaylLTF.

" f-The lock magnet 'IWL becomes energized when '-coded-c urrent isreceived from both'ends of the block, over the circuit from terminal Bat front contact b'of relay 'ITR over contacts at of relays 'IRTB andILTB and contacts 46-41, lifting the locking dog 21 to unlock theswitch'lever 8.

When the switching is completed, with the train occupying the main trackready to proceed in the established direction, which is toward the rightunder the conditions assumed, the operator is advised by the train crewthat switch lWis locked normal and he then restores lever TSW to itsnormal center position, completing a circuit in Fig. 1B momentarily fromterminal .3 over contacts a'and g of lever 'ISW, front contact 7' ofrelay 4RFK through relay 3ST to terminal C, energizing relay 3ST to.transmit a control code to the left-hand end of the block in whichchannel 2 is not energized. Relay 4LFS isreleased by this code,deenergizing the coded track sections in the rear of the train.

Since signal BR has been cleared, as the train proceeds, relay BRS willbecome .energizedsto supply 75 code to the section in the rear of signal8R to condition signal BR to indicate caution, causing code tobe'supplied' to the section'in the rear of signal BR to energize relays4RH and 4RDA to permit signal 4RA to. be cleared for a following train.

' When the block is vacated, relay 4RD becomes energized in place ofrelay 4RDA to transmit: a block clear indication to the ofiice toenergize relay 4RBK, which operates to restore the system to itsinactive condition as hereinbefore described. 1

It may be that an unlock is requested by the crew of a train at switch1W when the trackway system is set up and the block is occupied by amain line train whichhas passed the switch location, moving from left toright, for example.

In this case relay 4RFK is energized, and the movement of the switchlever ISW to its righthand position results in the transmission of onlyone code, namely, to Station No. 2 at the lefthand end of the block, thecircuit by which relay IST is energized by operation of lever 'ISW beingopen at back contact ;i of relay. 4RFK.

When the main line train is between signals BR and 8R, relay BRS isenergized, and if at this time steady current is supplied to the railsof the section in the rear to pick up relay BLTF, relay BWS will pick upthe circuit extending from terminal B at contact e of relay GLTF overcontact d of relay GRS, through relay BWS to terminal c and relay BRSwill then release, due to the opening of back contact I) of relay GWS.Relay 6LC'I therefore operates as already described to supply steadycurrent, followedby code, to the rails of the section at the right topick up relay TLTR, and eventually relay 'ILTB, provided the portion ofthe block at the left of switch 1W is vacant. In the portion atthejright vacated the section in the rear of that signal.

In the foregoing examples, it has been assumed that the train which hasentered the main line via switch 1W is to proceed in the establisheddirection of traffic, but it maybe desired to have this train move inthe opposite direction- This is permissible, since the clearing ofsignal 6L as well as that of signal 8R has been effected as the resultof the movement of the switch lever ISW to its right-hand position.

When an against-traffic move is to be made; the operator holds lever'ISW reversed until he knows that the train has passed the intermediatesignals such as signal 6L, as indicated by the lighting of lamp 3TKE,for example. When the train moving toward the left passes signal 6L,relay SLTR is shunted and its code operation ceases, releasing relayBLTF which in turn releases relay SWS. Relay BWS is slow to release andthe clsing of its back contact b in the circuit for the directionalstick relay SLS is thereby delayed sufficiently to prevent theenergization of relay SLS, so that coded ener is not supplied to thelefthand end of the section in the rear of signal BL when this sectionis vacated, to conflict with that supplied to the block at theright-hand end by relay TRCT.

It follows that when the train moving toward the left vacates thesection at the rear of signal Li, relay BRTR responds to the codedcurrent supplied by relay 'IRCT to cause relay fiRCT to supply codedcurrent to the section in the rear of signal ER, and to energize relaysBRH and 6D to clear signal 6R in the rear of the train.

When the train moving toward the left enters section 3T, the release ofrelays 3TB and 3TP stops the code operation of relay SLOT. If theoperator does not now restore lever JSW to normal to initiate therestoration of the system to its normal inactive condition, relay ARTRwill 9 respond to the coded current received over the track rails fromthe right, when the rear of the train passes signal 4LA, to energizerelay ARTE, and the stick circuit for relay DLES will then be opened atback contact 0 of relay ARTE, since back contact d of relay 4W8, inparallel therewith, is open.- Relay MES therefore releases and in turnreleases relay EW S, which prevents further operation of relay aLCT.Relay lRTR responds to the code received from the rails of the sectionat the right, and energizes relay 4RD to initiate the transmission of ablock clear indicati'on code to the office, and the system is thus leftin the same condition as when a signal lever is left reversed after thetrain vacates the block.

When the switch lock circuits of Fig. 2D are interposed between Figs. 20and 2E as above described, it will be seen that the lighting circuit forsignal 835 or 6L will not become closed until an approaching train haspassed the location of switch TW, and consequently these circuits aresuitable for use only when the coded track sectior'i between the switchlocation and the nearest signal is of sufficient length to provide thedeseated over the coded track section between the switch and the nearbysignal by employing a reverse feed back code in that section, asillustrated more particularly in Fig. 2F.

In Fig. 2F, the hand throw switch 9W. is assinned tote a relativelyshort distance from the signals ML and MR, and for simplicity it will beassumed that Fig. 235 is located between Figs. 23 and 2A t6 illustratethe circuits for a single track block containing but one pair ofintermediate signals "IL and JR, the corresponding dmce circuits beingthose of Figs. 13 and 1A as in mepreceding example, with the electricswitch lock for switch QW controlled by level" 18W,

20 since but one. switch lock lever is required per block, as alreadypointed out.

Assuming first that the operator moves lever ASE; to the right andpresses the starting button ZSTB to effect the clearing of signal 4RAfor a throughtrain movement through the block illustrated by Figs. 2B,2B and 2A, control codes will be transmitted as hereinbefore describedto energize relay GRHS at the left-hand or entrance end, and to alsoenergize relay [RPS at the right hand or exit end, relay ZRFSP becomingenergized and setting relay ERCT into operation to supply coded currentto the track rails at the right-hand end.

In Fig. 2F, the code following track relay WRTR responds, energizing therepeating relay IORTF and the code detector relay MRI-I in the normalmanner. Relay MRI-I completes circuits for mechanism HlRG for clearingsignal IGR, and energizes the code transmitter 8601 to cause relay IDRCTto supply coded current to the rails of the short section in the rear ofsignal {OR to which the track relay QRTR at the switch locationresponds. 7 Relay BRTR energizes the slow release relays QRTF and QRTBover its contact a, and operates relay iiRCT by the periodic closing ofits back contact 22 to repeat the code in the section at the left ofswitch SW7, provided the switch indication relay QNWP andthe track relay9TH, are energized, so that relay ARTR in Fig. 2B is supplied with codedcurrent to effect the clearing of signal ERA in the usual manner.

The circuit for relay SRCT extends from terminal B at back contact b ofrelay SLTR over back contact 2) of relay QRTR, front contact aof relayQRTB, back contacts 17 of relays EJLTB and eLTF front contact a. ofrelay 9TH, front contests '0 of relays 9NWP -and QRT-F through re- QRC'Ito terminal C. The approach relay QRAR is connected across the trackrails of the section to which code is being supplied by relay 936T, andis adjusted like relay lRAR so that unless it is shunted by anapproaching train within range of the signal inadvance, which in thisinstance is signal lDR, relay SRA-R responds to the code and energizesthe slow release relay iiRAP, the eircuit for relay BRA extending fromterminal B at back contact a of relay QLTBover front contacts a ofrelays QRTB and QRAR through relay QRAP- to terminal C. By closing itsfront contact h, relay SRAP prepares a circuit over which relay QLCT isenergized momentarily, in parallel with relay QRCT, each time relayQRTR, releases. Each energization of relay QLCT is of brief durationbecause its circuit is opened at back contact 0 of relay QRCT as soon asrelay BRCT picks up. Relay 9LCT therefore supplies a brief feed backimpulse to the rails of the section extending to signal HER, during eachinterval between the impulses or the code supplied thereto by relaylilRC'l, to energize relay IO LTR, which relay is then held energizedlocally for the remainder of such interval over a local stick circuit from terminal B at back contact 0 of relay iElRCT, contact g of relay IURI-l, or contact e of relay I HRS, and contact a and the lower windingof relay 'lcL'IRto terminal C. The closing of front contact Prof relayHlRI-I or of front contact f of relay MRS connects relay IORAR to thedecoding transf ormer associated with relay IQLTli, in place of relayldLl-l, so that relay IERAR and its repeating relay IGRAP becomeenergized when relay HJLTR is operated by feed back impulses. When atrain approaching switch 9W from the left reaches a pointwhere theresistance of the shunt comprising its wheels and axles and the rails ofthe intervening track is'reduced so that relay 9RAR fails to respond tothe code supplied by relay ,SRCT, relay BRAP releases to stop thetransmission of feed back impulses over the rails of the section inadvance, thereby releasing relays HIRAR and IORAP, the lamp for signalIllR becoming lighted when back contact I) of relay IDRAP closes. Theapproach lighting distance for signal 4R therefore extends to :a pointat the left of switch 9W determined by the adjustment of relay BRAR.

With respect to train movements in the opposite direction, from right toleft, the operation of the apparatus of Fig. 2F is similar to that ofFigs. 2D and 2E as already described.

I shall now assume that the operator wishes to permit a train to enterthe main track via switch SW, and so moves the switch lever 'ISW to itsright-hand position to set up the direction for movements toward theright as already described in connection with the control of switch 1W.In the present example, the trackway circuits as shown in Figs. 23, 2Fand 2A will be set up in the same manner as for clearing signal IRA, butsince the signal lever 4R has not been reversed, the receipt of a blockclear code at the ofilce in response to the energization of relay 4RDresults in the transmission of a control code to the entrance end toenergize relay 4LFS, which code finds relay 4RTF energized and soenergizes relays lTE and 4TES to apply steady current temporarily to thetrack rails at th left-hand end of the block, releasing relay 4RD totransmit a block occupied code to the office.

In Fig. 2F, relay 9LTR is energized by the current received from theleft during the first off period of the code delivered by relay SRCT,and relay QRCT remains released due to the Opening of back contact I) ofrelay BLTR, which also prevents further transmission of feed backimpulses by relay QLCT, thereby releasing relay IBRAR to cause signalIQR to become lighted and to energize the directional stick relay MRS.Since back contact a of relay QLTR is also open, relays 9RTF and QRTBrelease and relay QLTF becomes energized and by opening its back contact0, releases relay QNWP, assuming as in the preceding example, that thecrew of the train at the switch have removed the padlock bail 5D andthereby opened contact 49. Terminal B at back contact 0 of relay QNWPbecomes connected to the circuits for relays 9RTF and BRTB so that theserelays become energized in response to the continued operation of relaySRTR.

In Fig. 2B, relay lWS picks up after a short time to cause relay 4LCT tosupply coded current to the track at the'left-hand end of the block, asalready described, to cause relay BLTR to operaate periodically andenergize relay 9LTB, along with relay SLTF, the lock magnet BWL becomingenergized when relays QL'IB and BRTB are both energized to indicate thereception of coded current from both ends of the block. Since relayIDRAP has been released, if the train entering the main line moves inthe established direction,

toward the right, it finds signal IOR lighted to display its proceed orcaution indication.

When the operator is advised by the train crew that switch 9W has beenlocked normal, he restores lever 'ISW to normal, thereby transmitting acontrol code to release relay 4LFS and thereby deenergize the codedtrack circuits inthe rear of the train, and since relay IORSfiisenergized, '75 code will be supplied, to these'sections by relays HlRCTand QRCT as soon as section ST is vacated, so thatsignal 4RA or 4RBmaybe cleared for a following train.

If the train moves toward the left, against the established direction oftraffic, the operator leaves the switch lever QSW reversed until theblock is vacated. Relay 9RAR responds to the codesupplied to the trackin the rear of the train to reenergize relay IGRAR, thereby releasing.relay IEIRS, and the system is then restored to normal in the mannerhereinbefore described in connection with switch 1W.

The circuits of Fig. 2F involved in the operation of the system fortraflic movements from right to'left function like=the correspondingcircuits of Figs. 2D and 2E, and a detailed descriptionthereof is deemedunnecessary.

In the foregoing, I have described a centralized trafiic control systemembodying my invention in connection with a system of reversiblecircuits employing the track rails as the conductors over which thesignals. are controlled. It .will be understood that these conductorsmay also be line wires in which casethe circuits would include frontcontacts of normally energized track relays, a suitable arrangementbeing shown, for example, in my Letters Patent of the United States No.2,326,991, issued Agigust 1'7, 1943, for Railway Trafiic ControllingApparatus.

Although I have herein shown and described only one form of railwaytraffic controlling apparatus embodying my invention together withmodifications thereof as applied to difierent situations, it isunderstood that various changes and modifications may be made thereinwithin the scope of the appended claims without departing from thespirit and scope of my invention.

Having thus described my invention, what I claim is: y

1. Railway traflic controlling apparatus for governing the operationof-railway signals located at opposite ends of a stretch of singletrack, comprising a normally deenergized system of reversible circuitsextending the length of the stretch which is arranged to be energized ateither end to control the signal at the other end in accordance withtraflic conditions in the stretch, a signal lever for each signallocated at a central ofiice for imposing manual control upon thesignals, signal indication means at the oflice controlled by saidsignals to indicate their condition, two block indication relays at theoflice controlled by said system of circuits from the opposite ends ofthe stretch, two direction locking relays, one controlled by each blockindication relay, indication means controlled by said direction lockingrelays to indicate, when a selected traffic direction is established,whether the stretch is occupied or clear, a remote control system havinga manually controllable starting button for each signal lever, twostarting circuits controlled by each starting button for initiating thetransmission of two control codes by said remote control system when theassociated signal lever is operated to a reverse position including onewhich serves to energize said system of circuits in the directionrequired for the; control of the signal governed by the operated leverand another which serves to render such signal responsive to traflicconditions as reflected by said system of circuits, the starting circuitfor. said one. control code including contacts of both direction lockingaceaeee relays, whereby each direction locking relay when operatedrenders said remote control system inefiective tochange the condition ofsaid system of circuits, means effective when either signal lever isreversed for operating the direction locking relay for the trafiicdirection governed by such lever in response to a block clear indicationreceived. by the associated block indication relay, means for releasingsaid direction locking relay effective only when said block indicationmeans indicates that the block is clear, the last operated signal leveroccupies its normal position and said signal indication means indicatesthat the signals controlled thereby are at stop, a starting circuitcontrolled by each direction locking relay for automatically initiatingthe transmission of a control code by said remote control system whichserves to restore said system of circuits to its normally deenergizedcondition, and means controlled by the associated block indication relayfor completing such starting circuit concurrently with the release ofsaid direction locking relay.

2. Railway traffic controlling apparatus for governing the operation ofrailway signals located at opposite ends of a trafiic block, comprisingan electroresponsive device at the location of each signal forcontrolling such signal, a normally deenergizecl system of reversiblecircuits extending the length of the block and arranged to be energizedat either end to control the electroresponsive device at the other endin accordance with traiiic conditions in said block, a traific r lay ateach signal location which in a first position renders the signal atthat location responsive to trailic conditions in said block by enablingthe energization of the associated electroresponsive device over saidsystem of circuits and in a second position effects the energization ofsaid system of circuits in the direction required for the control of theelectroresponsive device at the other end of the block, a signal leverfor each signal located at a control ofiice, a communication system fortransmitting control codes to said signal locations for controlling saidsignals in accordance with the positions of said levers and fortransmitting indication codes to said oflice which reflect the conditionof said signals and also of said electroresponsive devices to indicatethe condition of said trafiic relays and whether or not the block isoccupied, a starting button for each signal lever for initiating thetransmission of a control code to the location of the correspondingsignal which reflect the position of such lever, means responsive to theoperation of each starting button when the associated signal lever isreversed for initiating the transmission of a control. code whichrenders the signal controlled thereby responsive to the energization oithe associated electroresponsive device, and in the event both trafficrelays are in their first position for additionally initiating thetransmission oi a second control code which opcrates the traflic relayassociated with the other signal to its second position, and means atsaid ofiice rendered efiective upon. the reception of indication codesindicating. that the block is vacant and that the operated signal habeen restored to its stop position, and also dependent upon therestoration of the operated lever to its normal position forautomatically initiating the transmission ofa. third control code bywhich the operated traiiic relay is restored to its first position.

3. Railway traflic. controlling apparatus for governing the operation ofrailway signals located at opposite ends of a traffic block, comprisinga normally deenergized system of reversible circuits for controllingelectroresponsive de*- vices at the locations of said signals inaccordance with trafflc conditions in said block, a traffic relay ateach signal location which in a normal position renders the associatedelectroresponsive device responsive to the energization of said systemof circuits and in a reverse position effects the energization of saidsystem of circuits in the direction required for the control of theelectroresponsive device at the other end of the block, control leversfor said signals located at a control ofdce, a remote control systemcontrolled by said levers having means associatedwith said signal leverfor manually initiating the transmission of control codes forselectively operating the traffic relay at either end of the block toits reverse position and for rendering the signal at the other end ofthe block responsive to the energization of the associatedelectroresponsive device, said remote control system also includingindication means at the ofiice operated automatically by said remotecontrol system to indicate the condition of said electroresponsivedevices and of said signals, whereby either signal may be manuallycleared to permit a train to enter the block and its condition and themovement of a train governed thereby is indicated automatically at saidofiice, and means at said office controlled by said indication means andrendered effective by the return of such sig-' nal to its stop positionand by the return of its control lever to normal following the movementof a train into the block for automatically initiating the transmissionof a control code for restoring the operated traffic relay to its normalposition in response to the operation of said in dication means whensaid train vacates the block.

4. Railway traiiic controlling apparatus comprising an electroresponsivedevice at each end of a traffic block, a normally inactive system ofreversible circuits for controlling said devices, a; trafiic relay ateach end of the block, means controlled by each traffic relay whenoperated to render said system of circuits active to control the deviceat the other end in accordance with traffic conditions in said block, ablock indication relay and a direction locking relay for each saiddevice located at a control oifice, manually operable control means atsaid oifice, means rendering' the operation of said control meansefiective only when both direction locking relays are released toselectively operate the trafiic relay at either end of the block tothereby energize the electroresponsive device at the opposite endprovided the block is unoccupied, means con trolled by eachelectroresponsi've device when so energized for energizing the blockindication and direction locking relays associated therewith, meanspreventing a change in the condition of either trafiic relay as long aseither direction locking relay is energized, a direction indicator lampfor each direction and a block indicator lamp located at said ofiice,energizing circuits for said block indicator lamp each including a backcontact of one of said block indication relays and in series therewith afront contact of the associated direction locking relay, an energizingcircuit for each direction indicator lamp including front contacts ofthe corresponding block indication and direction locking relays inparal-

